In Unicode, the Private Use Areas (PUA) are three blocks that are not assigned characters by the standard. The three blocks are Private Use Area, in the Basic Multilingual Plane, Supplementary Private Use Area-A and Supplementary Private Use Area-B, the latter two being in and covering nearly all of planes 15 and 16, respectively. They are intentionally left undefined so that third parties may assign their own characters without conflicting with Unicode Standard assignments. Under the Unicode Stability Policy, the Private Use Areas will remain allocated for that purpose in all future Unicode versions.